Bit.



'No. 693,|l7. Patented Feb. 1|; I902.

F. H. DAVIS & c. A. TERRY.

fjNVENTi/LS UNITED STATES ATENT 'FFlCEe FRANCIS HARLEY DAVIS, OF NEWBURGH, AND COLEMAN A. TERRY, OF

' NEW YORK, N. Y.

BIT.

SPECIFICATION formingpart of Letters Patent No. 693,117, dated February 11,1902.

Application filed $eptember 22, 1900. Serial No. 30,814. (No model.)

To all whmn it may concern.-

Be it known that we, FRANCIS HARLEY D vIs,of Newburgh,in the county of Orange,and COLEMAN A. TERRY, of New York city, in the county of New York, State of New York, have invented certain new and useful Improvements in Mills or Bits; and we do hereby declare the following to be a full,clear,and exact description of the invention, such as will enable others skilled in the art to whichit appertains to make and use the same.

Ourinvention relates to an improvement in bits for core-boring apparatus, and more particularly to one in which shot is employed for cutting out the core, the object of the invention being to provide an improved mill or bit of this character to which the shot can be readily fed and which will accommodate itself to the wear, so that although it may become shorter it will still have practically the sameapplication on the shot to be conveyed with a rolling pulverizing motion underneath its surface; and a further object is to provide a coreboring apparatus with notches to guide the shot beneath the same and with a series of auxiliary notches or holes which will be automatically brought into operation as others wear.

With these objects in view the invention consists in certain novel features of construe- 1 represents our improved mill, which is provided on its inner and outer faces with parallel spiral grooves 2 and made at the lower ends of said parallel grooved portions with notches 4. These'notches 4 arepreferably made with a vertical wall 5 and an. in

clined wall 6, the vertical wall being in front of the inclined wall as the mill rotates, the

inclined wall at the rear serving to direct-the' hardened metal shot under the lower edge thereof. These hardenedshot or grains of metal are caused to roll or be drawn along beneath the mill under pressure of the drill and crumble or pulverize the stone, and the pulver ized stone is then carried up by the stream of water or compressed air induced from the top through the drill-rod.

A series of triangular notches or holes 7, similar in shape to notches 4, are arranged in the spirally-grooved portions of the mill or bit 1 and in different planes, so that when'one notch is worn out, or nearly so, another will .be brought into operation, thus dispensing with the necessity of withdrawing the mill or bit to deepen the notch or make new ones, as is the case with all devices of similar character heretofore known. r

In operation the shot will follow the grooves 2 in the inner face of the mill or bit, between the same and core being bored, to the lower end 'ofmill or bit, and will also follow in the grooves 2 in the outer face of mill or bit to the bottom thereof and be fed beneath the same by the notches 4l,as heretofore explained. Instead of constructing our improvements as above described we might make them as shown in Fig. 3. In this form of our invention mill or bit 8 is made on its inner and outer faces with parallel vertical grooves 9 for the passage of the shot and with triangular notches 10 in the lower ends of said grooved portions to guide the shotloeneath the bit or mill.

Various other slight changes might be resorted to in the general form and arrange ment of the several parts described without departing from the spirit and scope of our invention, and hence we do not wish to be-lim ited to the precise details set forth, but consider ourselves at liberty to make such slight changes and alterations as fairly fall within the spirit and scope of our invention.

side disposed vertically.

2. A bit, comprising a tubular body having a spiral groove in its wall, and having a seriesof triangular holes in the grooved portion, the sides of all the triangles disposed in planes parallel with the axis of the bit and the bases of said triangles disposed horizontally.

3. A bit comprising a tubular body having external elongated grooves and also having internal elongated grooves coincident with and corresponding in dimensions to the external grooves and holes in said grooved portion.

4.. A bit comprising a tubular body having external and coincident internal spiral grooves, and having triangular holes in the grooved portions, the. bases of the triangular holes being at right angles to the axis of the seam? 

